Biegun will travel to Seoul and Tokyo on Dec. 15-19 to meet his counterparts there and continue "close allied coordination" on the DPRK, according to a statement released by the department.
The special envoy's visit comes as a year-end deadline set by Pyongyang for Washington to change its policies looms.
The Korean Central News Agency also reported Sunday that the DPRK
carried out "a very important test" at the Sohae Satellite Launching Ground on Dec. 7.
In response, U.S. President Donald Trump said the DPRK side risks losing "everything" if it acts "in a hostile way."
Denuclearization negotiations between Washington and Pyongyang have stalled since the second summit between the DPRK's top leader Kim Jong Un and Trump in Hanoi in February ended without a deal. The two leaders first met in Singapore in June 2018.